Here's the question you clicked on:
Mello
Geometry~!
is ABCD a parallelogram or a rhombus?
the figure is not drawn to scale, so it's harder to see let me draw again and you can check to see if i am right. |dw:1355076484153:dw|
BD is perpendicular to AC since they are diagonals of a rhombus look at triangle ABD, the area is ABxDH = BDx(AC/2) since AC/2 = DH ==> AB = BD and since AB = AD also, (rhombus), triangle ABD have 3 sides equal, (they are called equalateral triangle right?), each angle is 60 degree so angle ABC = 2x60 = 120